: The Wishbone control arm is a type of independent suspension used in motor vehicles. The general function of control arms is to keep the wheels of a motor vehicle from uncontrollably swerving when the road conditions are not smooth. The control arm suspension normally consists of upper and lower arms. The upper and lower control arms have different structures based on the model and purpose of the vehicle. By many accounts, the lower control arm is the better shock absorber than the upper arm because of its position and load bearing capacities. It has an “A” shape on the bottom known as wishbone shape which carries most of the load from the shock received. The lower control arm takes most of the impact that the road has on the wheels of the motor vehicle. It either stores that impact or sends it to the coils of the suspension depending on its shape. During the actual working condition, the maximum load is transferred from upper wishbone arm to the lower arm which creates possibility of failure in the arm. Similarly, impact loading produces the bending which is not desirable. Hence it is essential to focus on the stress strain analysis study of lower wishbone arm to improve and modify the existing design. The present study will contribute in this problem by using finite element analysis approach.

1. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 7, Issue 2 (May. - Jun. 2013), PP 43-48
www.iosrjournals.org
www.iosrjournals.org 43 | Page
Experimental & Finite Element Analysis of Left Side Lower
Wishbone Arm of Independent Suspension System
Prof. A. M. Patil1
, Prof. A.S. Todkar2
, Prof. R. S .Mithari3
, Prof. V. V. Patil4
1234
Mechanical Engineering Department, T.K.I.E.T. Warananagar, Shivaji University,
Tal. Panhala, Dist. Kolhapur, India.
Abstract : The Wishbone control arm is a type of independent suspension used in motor vehicles. The general
function of control arms is to keep the wheels of a motor vehicle from uncontrollably swerving when the road
conditions are not smooth. The control arm suspension normally consists of upper and lower arms. The upper
and lower control arms have different structures based on the model and purpose of the vehicle. By many
accounts, the lower control arm is the better shock absorber than the upper arm because of its position and load
bearing capacities. It has an “A” shape on the bottom known as wishbone shape which carries most of the load
from the shock received. The lower control arm takes most of the impact that the road has on the wheels of the
motor vehicle. It either stores that impact or sends it to the coils of the suspension depending on its shape.
During the actual working condition, the maximum load is transferred from upper wishbone arm to the lower
arm which creates possibility of failure in the arm. Similarly, impact loading produces the bending which is not
desirable. Hence it is essential to focus on the stress strain analysis study of lower wishbone arm to improve and
modify the existing design. The present study will contribute in this problem by using finite element analysis
approach.
Keywords – Lower Wishbone Arm, Independent suspension, Finite Element Analysis, ANSYS software.
I. Introduction
The Lower Wishbone is also called A-arm. Wishbones can be used in an all wheel independent
suspension setup. Read on to know more a wishbone has two mountings on the chassis of a car and one to locate
the wheel it is connected to. Because two rods are used on the two mounting points it is called a double
wishbone setup. Double wishbones provide more stability to wheel movements at high speeds which reduces
camber angle as the wheel moves up and down over uneven surfaces. Wishbones can be very easily adjusted as
every joint can be tweaked for optimal wheel movement. In automobiles, a double wishbone (or upper and
lower A-arm) suspension is an independent suspension design using two (occasionally parallel) wishbone-
shaped arms to locate the wheel.
During the actual working condition, the maximum load is transferred from upper wishbone arm to the
lower arm which is possibility of failure & bending of lower wishbone arm at the ball joint location as well as
control arm because of high impact load by produces road condition which is not desirable. Hence it is essential
to focus on the stress strain analysis study of lower wishbone arm to improve and modify the existing design.
Also current conventional material (mild steel) is replaced by composite materials (Carbon fiber polymer).
The current car used double wishbone suspension arm built from mild steel and it can affect the weight of
vehicle. Therefore, in order to make new improvement and overcome this problem, a study about car suspension
has been carry away and it involving composite material. Carbon fiber polymer has proven for it strength
beyond the steel and provide less weight. By apply this fact; the study about car suspension in composite form
has taken place.
II. Solid Modeling Of Lower Wishbone Arm In Catia V5 R17
To carry out FEM analysis of any component, the solid model of the same is essential. It is also called
body in white. So the solid model of Independent Suspension is require and this can be done in special CAD
package like CATIA V5 R17.

2. Experimental & Finite Element Analysis of Left Side Lower Wishbone Arm of Independent Suspension
www.iosrjournals.org 44 | Page
Fig. 1.1 CATIA Modeling of Lower Wishbone Arm.
III. Stress Analysis Procedure In Fea:-
 The load applied on Lower Wishbone Arm is W1 = 4900N. Then stress analysis by ANASYS Software the
results are given by following fig.
Fig. 1.2 Stress in Lower Wishbone Arm in structural steel & composite material.
 GRAPHICAL REPRESENTATION OF STRESS AT DIFFERENT LOAD CONDITIONS IS
GIVEN BY.
SR.
NO.
LOAD (N) STRUCTURAL STEEL (Pa) COMPOSITE MATERIAL
(Pa)
1. 4900 5.1421e8 6.3719e8
2. 5500 5.7717e8 7.1522e8
3. 6000 6.2964e8 7.8024e8

3. Experimental & Finite Element Analysis of Left Side Lower Wishbone Arm of Independent Suspension
www.iosrjournals.org 45 | Page
STRESS (108
PA) VS LOAD (N) CURVE:-
 The load applied on Lower Wishbone Arm is W1 = 4900N. Then maximum & minimum strain values are
found by ANASYS the results are given by following fig.
Fig. 1.3 Strain in Lower Wishbone Arm in structural steel & composite material.
 GRAPHICAL REPRESENTATION OF STRAIN AT DIFFERENT LOAD CONDITIONS IS
GIVEN BY.
SR. NO. LOAD (N) STRUCTURAL STEEL COMPOSITE MATERIAL
1. 4900 0.002571 0.12804
2. 5500 0.002885 0.14372
3. 6000 0.0031482 0.15679
STRAIN VS LOAD (N) CURVE:-
4.5
5
5.5
6
6.5
7
7.5
8
4200 5200 6200
Stress108Pa
Load N
SturcturalSteel
(Pa)
Composite
Material(Pa)
0
0.05
0.1
0.15
0.2
4200 4700 5200 5700 6200
Strain
Load (N)
Composite
Material
Sturctural
Steel

4. Experimental & Finite Element Analysis of Left Side Lower Wishbone Arm of Independent Suspension
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 The load applied on Lower Wishbone Arm is W1 = 4900N. Then maximum & minimum total deformation
values are found by ANASYS the results are given by following fig.
Fig. 1.4 Total deformation in Lower Wishbone Arm in structural steel & composite material.
 GRAPHICAL REPRESENTATION OF TOTAL DEFORMATION AT DIFFERENT LOAD
CONDITIONS IS GIVEN BY.
SR. NO. LOAD (N) STRUCTURAL STEEL(m) COMPOSITE MATERIAL (m)
1. 4900 0.0056037 0.24123
2. 5500 0.0062898 0.27076
3. 6000 0.0068616 0.29538
GRAPH OF TOTAL DEFORMATION (M) VS LOAD (N)
Natural Frequency measurement by FFT Analyzer:
Frequency response Function of Independent Suspension Link gives the natural frequency at the peaks with
corresponding amplitude at respective location of accelerometer on the Link.
Fig.1.5 frequency graph at position near front control arm
0
0.03
0.06
0.09
0.12
0.15
0.18
0.21
0.24
0.27
0.3
4600 4900 5200 5500 5800 6100
TotalDeformation(m)
Load (N)
Composite
Material(m)
SturcturalSteel
(m)
FRIST POSITION FREQUENCY GRAPH
-100
-80
-60
-40
-20
0
20
0 500 1000 1500 2000 2500 3000
FREQUENCY
ACCELRATION

5. Experimental & Finite Element Analysis of Left Side Lower Wishbone Arm of Independent Suspension
www.iosrjournals.org 47 | Page
Fig.1.6 frequency graph at position near rear control arm.
Fig.1.7 frequency graph at position near wheel centre
Fig.1.8 frequency graph at all three position near front control arm
IV. Comparisons of Natural frequencies by FEM and Experimental Method.
In the present study modal analysis of Independent Suspension Link is done by Fem as well as
Experimental method. Now to obtain the validation for FEM result we can compare those with the experimental
results. The below table gives the comparison of natural frequencies obtained by Fem and Exponential method
along with percentage difference at error obtained for Independent Link.
SECOND POSITION FREQUENCY
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
0 500 1000 1500 2000 2500 3000
FREQUENCY
ACCELRATION
THIRD POSITION FREQUENCY GRAPH
-80
-70
-60
-50
-40
-30
-20
-10
0
0 500 1000 1500 2000 2500 3000
FREQUEN CY
ACCELRATION
Series1
FREQUENY GRAPH OF ALL THREE POSITION
-100
-80
-60
-40
-20
0
20
0 500 1000 1500 2000 2500 3000
FREQUENCY
ACCELRATION
FRIST POSITION SECOND POSITION THIRD POSITION

6. Experimental & Finite Element Analysis of Left Side Lower Wishbone Arm of Independent Suspension
www.iosrjournals.org 48 | Page
Sr.
No.
Natural Frequency by ANSYS
in Hz
Experimental Natural
Frequency in Hz
Percentage deviation
1 577.76 481.125 16.72
2 694.05 596.875 13.99
3 826.55 793.75 3.96
4 842.33 859.375 -2.02
5 1023.7 1071.875 -4.7
6 1185.1 1184.375 0.0061
7 1245.9 1378.125 -1
8 1329.3 1428.125 -7.38
9 1363.6 1490.46 -9.3
10 1485.1 1556 -4.7
Table 7.3: Comparison of Natural Frequencies by FEM and Experimental Method.
Fig.1.9 Comparison of Natural Frequencies
Remark: The Four channel F.F.T. Analyzer is used for experimentation. The average percentage deviation in
experimental natural frequencies and natural frequencies by ANSYS software are found to be 6.3756 %.
IV. Conclusion
Under the static load conditions deflection and stresses of steel lower wishbone arm and composite
lower wishbone arm are found with the great difference. Carbon fiber suspension control arms that meet the
same static requirements of the steel ones they replace. Deflection of Composite lower wishbone arm is high as
compared to steel lower wishbone arm with the same loading condition. The redesigned suspension arms
achieve an average weight saving of 27% with respect to the baseline steel arms. The natural frequency of
composite material lower wishbone arm is higher than steel wishbone arm.
Acknowledgements
I am thankful to my Co-author Prof. A .S. Todkar and Prof. R. S. Mithari in Mechanical Engineering Dept.,
TKIET, Warananagar, for their encouragement and support to carry out this work.
References
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Delhi 1999.
0
200
400
600
800
1000
1200
1400
1600
0 1 2 3 4 5 6 7 8 9 10 11 12
FrequencyinHz
Natural Frequency
by ANSYS in Hz
Experimental
Natural Frequency
in Hz